It is appreciated that compounds considered as candidates for further development as pharmaceuticals advantageously possess desirable biological properties, but also physical properties that adapt them for use in the manufacture of pharmaceutical products. For example, compounds that form stable solids, including crystalline solids may be more readily manufactured and formulated. It is further appreciated that individual physical forms of the compound that are stable and additionally that may be prepared substantially free of other physical forms may also be more readily manufactured and formulated. It is to be understood herein that different physical forms may have markedly different physical properties, such as different solubility characteristics, different bioavailabilities and/or biological exposure, different stability, and the like.
In US patent application publication number US 2006/0100164, there are disclosed certain macrolide antibiotic compounds. The foregoing publication, and each additional publication cited herein is incorporated herein by reference. One of these macrolides is a fluoroketolide having Chemical Abstracts Registry Number 760981-83-7, which is also known as CEM-101 and solithromycin. The preparation of an amorphous form of CEM-101 is described therein. An alternative preparation of CEM-101 is described in WO 2009/055557. CEM-101 has the following chemical structure:

It has been discovered herein that CEM-101 can be isolated in a variety of crystalline forms which provide illustrative embodiments of the invention. CEM-101 can be isolated in crystalline form as a material having a range of different physical properties, depending upon the method of isolation. This is because CEM-101 can exist in more than one crystalline form, i.e., it exhibits polymorphism. CEM-101 can be isolated in at least two crystalline forms, denoted herein as Form I and Form II, each of which is pure or substantially pure and/or free of or substantially free of the other form. Various mixtures of Form I and Form II can also be isolated. In addition, solids which are mixtures of one ore more crystalline materials and also include amorphous solids can be obtained.
More detailed listings of the peaks for each of Form I and Form II are provided below in Tables 1-4 in the Examples, in which peaks are denoted as % relative intensity (I/I0×100). It is to be understood that in the X-ray powder diffraction spectra the exact values measured for °2θ (or the corresponding d-spacings) may vary depending upon the particular sample analyzed and the particular analysis procedure used. A range of values of at least ±0.1°2θ, and in some cases at least ±0.2°2θ, may be typical. Measurements on independently prepared samples on different instruments may lead to variability which is greater than ±0.1°2θ and/or ±0.2°θ.